Weeks after a court-ordered overhaul of his office, an Arizona sheriff with a reputation for retaliation received a fax that critics say proves he was secretly investigating a judge who ruled against him in a racial profiling case.

The 2013 fax from an informant was written as a timeline of key developments in the profiling case: It cited the judge's assignment to the case, claimed federal authorities were wiretapping the phone of one of Sheriff Joe Arpaio's aides, and suggested both happened shortly after the U.S. Justice Department allegedly called the judge.

Arpaio's office went on to spend $250,000 investigating, despite questions about the informant's credibility. U.S. District Judge Murray Snow characterized the investigation as an attempt to construct a "bogus conspiracy theory" to discredit him.

The six-term sheriff has been accused in the past of investigating judges at odds with him. But recent court hearings that examined the fax marked the boldest public attempt to confront Arpaio on the recurring retaliation allegation.

An investigator on the case is set to testify Tuesday as contempt-of-court hearings resume over Arpaio's defiance of Snow's orders. The sheriff has acknowledged letting his officers conduct immigration patrols for 18 months after the judge ordered them stopped.

Earlier this month, Arpaio insisted he wasn't investigating the judge, saying the case instead focused on claims that someone tapped his phones and breached the bank information of thousands of people.

Arpaio testified that others in his office ran the investigation, and he often had trouble recalling details, such as whether an investigator warned him to back away from confidential informant Dennis Montgomery.

"I was intrigued about the wiretaps on me and my chief deputy, and that was my major concern," Arpaio said.

Critics say the allegation that Arpaio investigated Snow is easy to believe based on some of his previous actions.

Superior Court Judge Gary Donahoe was charged with bribery in 2009 in a case brought by the sheriff's office after Donahoe disqualified an Arpaio ally from an investigation.

Donahoe received a $1.2 million settlement from the county after the charges were dismissed. But he said Arpaio was never held accountable for the unfounded case that damaged his reputation and caused him to spend $125,000 on attorneys.

"He feels like he is above the law," the now-retired judge said. "He has no integrity. ... His tactic is, when he gets caught, is to say he knows nothing about it or doesn't remember."

Arpaio's office did not respond to an email seeking comment from the sheriff or a spokesman. Arpaio's lawyer Mel McDonald also did not respond to a request for comment on the investigation.

Sgt. Travis Anglin, an investigator who examined Montgomery's claims, testified that he warned Arpaio to distance himself from Montgomery.

Anglin said the sheriff refused his advice and profanely asked him who he thought he was.

Former Arpaio attorney Tim Casey testified he attended a meeting with the sheriff at which Montgomery's claims were discussed.

Casey said investigators at the meeting claimed there was a conspiracy against Arpaio that involved the judge - and that it could be proven if the agency continued working with Montgomery. The informant had said he could assist investigators with data from his work for the CIA.

Casey regarded Montgomery's claims as "hogwash" but said Arpaio had a different view.

"He said something that indicated that he was enthusiastic and it needed to be looked into," Casey said.

"Dennis is not a conman, but I'm not getting into the substance of it," Klayman said this summer.

In a conference call Monday with the judge, McDonald raised the possibility of getting criminal immunity for Mike Zullo, a volunteer sheriff's posse member who examined Montgomery's claims, in exchange for his testimony.

Zullo declined to answer many questions during a deposition and refused to turn over some documents. Snow said he was unlikely to grant immunity.

Arpaio's office pressed ahead with the investigation even though a top aide concluded Montgomery was stringing along investigators for more money. The agency paid Montgomery $120,000.

Under questioning from his attorney, Arpaio reflected on the complicated relationship between investigators and informants.

"Even though someone may have a bad reputation, (he) one day maybe gives you - give law enforcement - some credible information. But I didn't have much confidence in the - in that informer," Arpaio said.